It then crosses the Niagara River, where it encounters the international border with the United States and continues into New York as Interstate 190 (I-190).

Highway 405 serves to connect the northern end of I-190 in New York at the Lewiston–Queenston Bridge with the QEW, and therefore it follows a somewhat direct path between the two.

The opposing lanes, initially separated by a wide gap, converge towards each other to form a 15-metre (49 ft) grass median.

[5] The opposing lanes converge, with an Ontario Tall Wall separating them, and pass beneath Niagara Regional Road 102 (Stanley Avenue).

The freeway's lone interchange is with Stanley Avenue, and traffic continuing east must cross the Lewiston–Queenston Bridge into the United States.

[13] In 2004, the eastern end of the freeway was modified to permit the queueing of trucks at the border, with the addition of one lane to the eastbound carriageway beginning at Stanley Avenue.